FLINT, Mich. — All along, through months of complaints from residents of this city about the peculiar colors and odors they said were coming from their faucets, the overriding message from the authorities here was that the water would be just fine.

Yes, there had been a boil order when fecal coliform bacteria turned up in some neighborhoods last year. And yes, the extra chlorine that was pumped in to solve that problem seemed to create another one — increased levels of a different contaminant.

Still, the guidance from Flint officials about the temporary water supply they switched to in 2014 — partly to save money — sounded assuring. In a notice sent to residents in July, city officials declared: “This is not an emergency. If a situation arises where the water is no longer safe to drink, you will be notified within 24 hours.”

The soothing talk has vanished. In recent weeks, testing has shown increased levels of lead in the blood of some Flint children — and health officials pointed to the water as a possible source.

First, the city advised residents to run their water for five minutes before using it, to use only cold water for drinking and cooking, and to install lead-removing water filters. Then county officials issued an emergency advisory recommending that people not drink Flint’s water unless it is tested for lead or filtered.

And last Friday, after corroborating that lead levels had risen in some children, state officials called for the water to be tested at all Flint public schools and for stepped-up efforts to replace lead service lines; they also promised $1 million to provide filters.

Officials met here on Wednesday afternoon, and talks were underway, officials said, for additional solutions that could come as early as Thursday. Gov. Rick Snyder said on Twitter late Wednesday that he planned to make an announcement about the situation on Thursday morning.

Private groups have raced to donate bottled water to schools, where the water fountains are now shut off, as well as filters to families who cannot afford them. Saying “we’re just in a heck of a bind,” Robert J. Pickell, the Genesee County sheriff, began serving bottled water and food that need not be cooked in water to hundreds of inmates in the county jail. Some residents have begun washing their children and pets with bottled water.

And Flint’s mayor, Dayne Walling, who had attended a 2014 event to celebrate the switch to the new water supply, called for returning to the city’s old water supply and urged state officials to provide millions of dollars to help pay for it.

The contaminated water was just the latest blow to Flint, an economically battered city that has struggled for years with factory closings, job losses and population decline.

Along Saginaw Street downtown, where at least one business had an “un-leaded” sign posted by a jug of water, residents had lingering questions: Would filters really do enough to make the water safe? What about unfiltered showers? Could they rely on the water at work and at restaurants? And why had it taken so long for leaders to figure out that there was a problem?

“I don’t think people know what’s going on at all,” said Chris Thornton, 49, who described the first blast of water from his faucets some days as looking like urine, smelling like bleach and tasting of metal. After his wife, Ronda, 50, felt sick to her stomach for months, the Thorntons began buying jugs of bottled water, though the price — on top of an already steep water bill — has been overwhelming.

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LeeAnne Walters, watched by her son Garrett, uses bottled water to make pasta because her tap water is often brown. She said Garrett's twin, Gavin, 4, had lost weight and tested for elevated lead levels since Flint switched water sources.CreditLaura McDermott for The New York Times

“As far as my family,” Ronda Thornton said, “we’ve just given up on the city’s water.”

Flint’s water problems are tied inextricably to its fiscal woes. In 1960, nearly 200,000 people lived here. But auto plants closed, and the population has dropped by half. By 2011, Flint’s shrunken tax base and seemingly intractable budget problems prompted Mr. Snyder to appoint an emergency manager for the city. Over the next four years, the city had four managers overseeing operations. Along the way, the city switched its water supply.

For decades, the city bought water from Detroit, which treated water from Lake Huron, then piped it here, 70 miles to the northwest. But with the costs mounting, Flint’s leaders decided they could save millions by joining a new regional authority that would draw and treat its own water from Lake Huron.

There was one complication: Flint needed an alternative water supply from April 2014 until the new regional system is ready, probably next year. In the interim, Flint switched to using water from the Flint River, which state officials say had been a backup source in the past.

Ask residents about the Flint River, and many of them roll their eyes. They say it was once as a dumping ground for car parts, grocery carts and refrigerators. There have been significant improvements and intensive restoration campaigns in recent years, though a Flint River Fest set for Friday has been postponed, organizers said, given the “current drinking water crisis.”

Even now, state officials say that treated Flint River water is safe and capable of meeting state and federal standards. Officials say the problem may be that some of the aging pipes and service lines that carry water into Flint’s homes and businesses contain lead and are being corroded by water. The water Flint used to receive from Detroit was treated with chemicals intended to prevent such corrosion.

For months, questions about lead and other risks multiplied. “Everyone kept saying: ‘It’s safe! It’s safe! It’s safe!’ ” recalled Melissa Mays, a Flint resident who says she was sickened by the water and has helped organize residents over the issue.

Then in September, a researcher from Virginia Tech released findings from the water in hundreds of Flint homes showing elevated lead levels. Blood tests released by a local pediatrician — and corroborated last week by state officials analyzing their own testing — showed an increase in lead levels in children in some neighborhoods since 2014, when the city began drawing water from the river.

“We all have a concern about Flint’s drinking water in terms of what we’re seeing in terms of lead,” Mr. Snyder said last week.

Mr. Walling said that the move to river water occurred when an emergency manager controlled the city, though the City Council did vote for the city’s plans for a new, regional water system. He acknowledged supporting the move in a state of the city address, but said that he had not been given sufficient information about the safety risks.

“I had to work with what I knew at the time,” Mr. Walling, who is up for election next month, said in an interview.

But for many residents, the authorities failed the city by taking so long to react. “Anytime you have to weigh money against the health and welfare of people, it always has to be the health and welfare you go with,” said the Rev. Alfred Harris, a local pastor who has stopped conducting baptisms at his church because of concerns about the water. “We’ve been talking about this for the last 14 months, and they did not give a sincere ear to any of us. Shame on you!”

LeeAnne Walters said her son, Gavin, 4, who has immune system issues, had suffered direct consequences. After the switch to river water, which sometimes looked brown in their house, Gavin dropped to 27 pounds, far below the weight of his twin brother, she said. He sometimes seemed unable to pronounce words he knew, she said, and then test results showed an elevated lead level in his blood.

“He is going to deal with the side effects of this for the rest of his life,” Ms. Walters said. “I don’t think there’s a word angry enough to describe my anger. I trusted the city, and I helped the city poison my kid. Who thought this could happen in the United States?”

Correction:

A picture caption on Thursday with an article about fears about lead in the water in Flint, Mich., misidentified the child pictured with LeeAnne Walters, who was shown using bottled water to make pasta. He is her son Garrett, not his twin, Gavin.

A version of this article appears in print on , on Page A18 of the New York edition with the headline: Flint’s Water Is Linked to High Lead in Children. Order Reprints | Today’s Paper | Subscribe